One of the challenges to sustainability is the management of textile waste. Effective technologies for recycling this type of waste are still lacking. Currently, textile waste is most often landfilled or incinerated. Pyrolysis offers a more advantageous solution, as it enables partial recovery of raw materials along with energy recovery from the remaining mass, thereby aligning with the circular economy. The kinetics of volatile matter release play an important role in the pyrolysis and combustion of solid substances. This paper presents research related to this issue. The study concerns three waste textile materials (cotton, silk, and polyamide) and the following process parameters: temperatures from 400 to 800 degrees C and time from 0 to 900 s. The results of the study are characteristics, i.e., functions describing the kinetics of volatile matter release as a function of process parameters. The general forms of these functions were determined taking into account fundamental physical and chemical laws. In addition to process parameters, the functions include coefficients whose values were determined on the basis of experimental measurements. The characteristics were determined for isothermal processes as well as for generalized processes, additionally accounting for temperature variability, which represents an original contribution of this study. Kinetic coefficients were derived from the obtained characteristics. The studies revealed mass fractions of volatile matter exceeding even 90%. The obtained characteristics may serve as tools for improving the sustainable management of textile waste by enabling more rational control of thermal processes.

When burning fuel in grate furnaces, supplying the right amount of air to them is as important as the method of air supply. In a furnace with a fixed grate, the supply method of primary air is determined by the distribution of the supplied air stream over time, and in a furnace with a movable grate, the said method involves the distribution of the stream along the active length of the grate. The need to account for air distribution is attributable to complex processes that occur during the combustion process. The paper describes experimental studies aimed at determining the influence of the distribution of the supplied primary air on the emission of CO2, CO, SO2, NOx, and on the content of combustible parts in the slag. In all cases, the total amount of primary air supplied to the process as well as other process control parameters was identical, and only the distribution of primary air was different. The paper proposes the use of a generalized function to describe the distribution of air, defined by its total demand and the relative time R that fuel remains on the grate until the maximum air stream is obtained. The quantity R was accepted at the value ranging from 1/6 to 2/3. With the rise of R, the emissions of CO2, CO, and SO2 increased by 53%, 125%, and 27%, respectively, and the emissions of NOx and the share of combustibles in the slag decreased by 12% and 79%, respectively.

One group of plants commonly used for solids combustion are grate furnaces. These furnaces come in numerous design solutions, dedicated to fuels with different properties and plants with different capacities. The use of grate furnaces presents the as-yet unresolved challenge of how to ensure the most favourable air distribution along the length of the grate. The paper proposes a design solution to ensure proper air distribution along the length of the grate. An additional advantage of the proposed solution is the intensification of heat exchange in the furnace, enabling the boiler's circulating medium to be heated more efficiently. Both of the advantages allow an increase in the energy efficiency of the plant and therefore contribute to a reduction in the amount of fuel burned and CO2 emissions.

One of the actions popularized worldwide to reduce the consumption of fossil fuels is the combustion of renewable fuels and the co-combustion of both of these fuels. To properly implement combustion and co-combustion processes in power-generation installations, operational characteristics, including emission characteristics are required. To determine these characteristics, tests must be conducted, within the scope of which, for individual operating stages of the installation's work, the readings collected from a relatively large number of control and measurement instruments should be taken into account. All these instruments have different levels of accuracy, which, among other factors, bring about lower adequacy of the characteristics determined on the basis of these measurements. The objective of this study is to present possible adaptations of data validation and reconciliation methods to increase the adequacy of emission characteristics for the process of co-combustion of fuels. The methodology is discussed based on the example of studies on the co-combustion process of sewage sludge with coal in a grate furnace. The aforementioned characteristics were determined based on measurement tests of gaseous emissions of flue gas components. The tests were carried out for various preset operational conditions of the process, such as the thickness of fuel layer on the grate, the share of sludge in the fuel, the humidity of the sludge, the theoretical ratio of excess air to combustion, and the distribution of air stream during the process. The research object is described and detailed research results concerning two exemplary measurement tests are given, as well as the most important results referring to the whole research. The performed calculations indicate the necessity to take into account often significant corrections, which can amount to about 10% of the measured value.

Multi-criteria decision analysis (MCDA) is a widely adopted tool, which is regarded as a suitable set of methods to evaluate sustainability in a variety of energy applications. The MCDA is usually performed employing a deterministic approach. Such an approach is rather not adequate to include model uncertainties connected with both: decision maker preferences (criteria weights) and process input data. By considering the stochastic nature of uncertainties, it is possible to generate results that can easily be analyzed statistically. In addition, such an approach allows investigating the consequences of the resulting uncertainty of multi-attribute aggregation on the final decision. In this study, we define, analyze and compare four different technologies of biodiesel production from used cooking oil (UCO) using probabilistic MCDA. Among the criteria, we consider energy, economic, environmental, as well as social aspects. To evaluate the uncertainty of the final results, we propose a novel method, coupling Monte Carlo simulation and method of data reconciliation. Firstly, we present the results of the deterministic case, in which we assume the exact values of criteria and the preferences. Besides, we investigate on a sensitivity of the results to identify the major factors affecting the economic, energy, environmental and social viability of biodiesel production. Furthermore, we conduct an analysis of the contributions of the different phases of the UCO processing to the resulting criteria. Finally, we introduce inaccurate or uncertain criteria values and criteria preferences to evaluate the uncertainty of the results. (C) 2017 Elsevier Ltd. All rights reserved.

One of the ways used to reduce the emission of carbon dioxide and other harmful substances is the implementation of biomass co-firing processes with coals. Such processes have been implemented for many years throughout many countries of the world, and have included using existing high-power coal boilers. Despite numerous experiments, there are still no analyses in the literature allowing for their generalization. The purpose of this paper is to determine the generalized energy and ecological characteristics of dust steam boilers co-firing hard coal with biomass. The energy characteristics determined in the paper are the dependence of the gross energy efficiency of boilers on such decision parameters as their efficiency and the share of biomass chemical energy in fuel. However, the ecological characteristics are the dependence of emission streams: CO, NOx, SO2, and dust on the same decision parameters. From a mathematical point of view, the characteristics are approximation functions between the efficiency values obtained from the measurements and the emission streams of the analysed harmful substances and the corresponding values of the decision parameters. Second-degree polynomials are assumed in this paper as approximation functions. Therefore, determining the characteristics came down to determining the constant coefficients occurring in these polynomials, the so-called structural parameters. The fit of the determined characteristics was assessed based on the coefficients of random variation and the test of estimated significance of structural parameters. Boiler characteristics can be used when forecasting the impact of changes in operating conditions on the effects achieved in existing, modernized, and designed boilers. The generalization of the characteristics was obtained from the measurement results presented in 10 independent sources used to determine them.

Abstract The publication analyses and evaluates the impact of the implementation of circular economy on the economy and especially on its mining and power generation sector in Poland. Circular economy is a relatively new concept concerning an innovative economic development model. The publication briefly describes the concept of circular economy. Among other things, the basic economic processes that make up circular economy are discussed. In addition, history is presented as well as examples of legislation that have had the strongest impact on the implementation of circular economy in the EU are identified. Further on in the paper, the impact that circular economy will have on the mining and power generation industry in Poland is discussed. Areas have been identified that will need the most attention in relation to the implementation of circular economy. It was pointed out that in the mining and power generation sector the scale of use of current and landfill waste should be increased as a priority. Attention has been paid to the necessary reduction of water demand and rational water and sewage management. Examples of use of mining gas and ventilation air have been discussed. The publication provides examples of a number of measures taken in accordance with circular economy. It was pointed out that there is still a need to popularize the existing ones and to look for new technical and organizational solutions conducive to the introduction of this new economic model. An important aspect of the impact of the circular economy on these sectors will be the decrease in energy demand resulting from the widespread implementation of the new economic model. For those already struggling with a number of problems of some of the mining and power generation sectors based on coal mining and combustion in Poland, the implementation of circular economy will pose another challenge.

The combustion process in grate furnaces is determined by a number of independent factors (control parameters). The results of this process are dependent factors (effects). The knowledge of the simultaneous impact of all of the aforementioned independent factors on all of the analyzed dependent factors is required for the analytical use of grate furnaces. The functions that define this relationship are identified as process characteristics. In this study, the analytical experimental methods of specifying characteristics will be discussed. This consists of two stages. The first stage is based on defining the numerical shape of the functions of the aforementioned characteristics. Worth noting is that constant coefficients can and do coexist with both independent and dependent factors. The second stage is based on specifying the values of the measured coefficients by means of statistical methods, as well as evaluating their relevance. Moreover, the second stage also consists of evaluating how adequate the specified characteristics will be in relation to the results. The aforementioned characteristics are input-output dependencies. The main introductory element of this paper is to define the use of more modern methods in designing scientific experiments. Another significant element is the use of a new and innovative function of distributing the air stream across the length of the grate. The suggested method of specifying characteristics has been exemplified in the test grate furnace by characteristics of NO emissions. Its efficiency was at the level of 100 kW during the co-combustion of coal and sewage sludge. The process characteristics of both fuel combustion and co-combustion in grate furnaces have a vital impact due to the number of existing facilities. Knowing the characteristics enables a dynamic regulation (online), as well as technical, ecological and economic optimization of the conditions of exploiting grate furnaces.

The Polish as well as the global energy economy, including in particular heat generation, is to a great extent based on facilities for the combustion of liquid and gaseous fuels. Globally, a considerable part, and in Poland a vast majority of these facilities are much worn out, and, consequently, they work with low efficiency producing considerable amounts of pollutants, which have a very negative impact on the environment. Therefore, it is of crucial importance to develop innovative solutions that enhance the efficiency of fuel combustion and at the same time reduce emission of pollutants. The paper presents a solution which renders it possible to increase the efficiency of fuel conversion by heating up substrates of combustion processes, heat recovery from combustion gases as a result of their cooling and water vapor condensation and which contributes to a reduction of pollution. The solution brings about significant fuel consumption savings and thus a considerable enhancement of economic and ecological efficiency of heat sources is achieved. The solution is specially dedicated to heat sources of low and medium power. The technology developed and described herein will also allow an elimination of environmental burdens caused by inefficient heat sources already in operation.

The article presents the method of utilization of rubber waste consisting in the production of coke from a mixture of hard coal and rubber waste from ground tires. In the coke obtained this way, the properties of the coal and rubber mixture were tested, the following indices were determined: reduction properties - CRI and coke strength after the reaction test - CRS.

In this article, to assess the use of renewable energy sources, the method of social efficiency of substituting non-renewable fuels with renewable energy sources was used. Social efficiency means the difference of energy-environmental, economic or sociological effects connected with producing the same amount of usable product in conditions of applying reference fuel and renewable substitute energy source. The amount of useful product should equal the use of one substitute energy unit. The proposed method constitutes a generalization of the existing method of economic effect evaluation on the basis of the Economic Efficiency of Energy Substitution indicators (EEES). Furthermore, the relations of calculations which enable defining dimensionless indexes for the effects of interest and method of standardization of the social efficiency index were described. The procedure is applied for the evaluation of renewable energy sources (solar energy in solar collectors, boilers powered by biofuels and heat pumps using geothermal energy) to prepare hot tap water.

Streszczenie. W artykule przeprowadzono analizę skutków ekologicznych substytucji paliwa nieodnawialnego (paliwa odniesienia) przez rozpatrywane odnawialne źródła energii (OZE), wykorzystując pojęcie społecznego wskaźnika efektywności oraz kosztu termoekologicznego, przy wytwarzaniu rozpatrywanego produktu użytecznego w zastosowaniu komunalno-bytowym. Przez społeczny wskaźnik efektu określonego rodzaju, rozumie się różnicę tego efektu w przypadku wytwarzania tej samej ilości produktu użytecznego przy stosowaniu paliwa odniesienia i energii substytucyjnej. Ilość produktu użytecznego powinna odpowiadać zastosowaniu jednej jednostki energii substytucyjnej. Analiza bezpośredniego zużycia energii nie obejmuje całkowitej energii niezbędnej do wytworzenia danego użytecznego nośnika energii. Jako miernik wyczerpywania nieodnawialnych bogactw naturalnych można przyjąć tak zwany wskaźnik kosztu termoekologicznego, który powinien być wyrażany za pomocą skumulowanych wskaźników zużycia energii. W opracowaniu przedstawiono metodologię obliczeń oraz przykład aplikacyjny związany z wykorzystaniem wybranych źródeł energii odnawialnej (energii słonecznej w kolektorach słonecznych, kotłów zasilanych biopaliwami, oraz pomp ciepła wykorzystujących energię geotermalną) do przygotowania ciepłej wody użytkowej u odbiorcy indywidualnego, a także porównano uzyskane wyniki z istniejącą metodologią dotyczącą obliczania charakterystyki energetycznej budynków.

The multicriteria decision process consists of five main steps: definition of the optimisation problem, determination of the weight structure of the decision criteria, design of the evaluation matrix, selection of the optimal evaluation method and ranking of solutions. It is often difficult to obtain the optimal solution to a multicriterion problem. The main reason is the subjective element of the model – the weight functions of the decision criteria. Expert opinions are usually taken into account in their determination. The aim of this article is to present a novel method of minimizing the uncertainty of the weights of the decision criteria using Monte Carlo simulation and method of data reconciliation. The proposed method is illustrated by the example of multicriterion social effectiveness evaluation for electric power supply to a building using renewable energy sources.

This paper presents an optimisation method for a strategy for fuel feeding in combined heat and power plant boilers with regard to the trading effects of CO2 allowances. A detailed analysis has been conducted on an exemplary (combined heat and power plant) CHP that is equipped with OPG-230 multifuel steam boilers adapted for metallurgical fuel gases. The CHP cooperates with a steelworks nearby. A special feature of the CHP activity is the consumption of large quantities of gases that are generated as byproducts in the production of pig iron (blast-furnace gas), steel (converter gas in the steelworks) and coke (coke-oven gas at the nearby coke ovens). These gases are co-incinerated with coal at the CHR In the optimisation performed, the input data had a heuristic, probabilistic nature, and constant (averaged) data have been used. (C) 2013 Elsevier Ltd. All rights reserved.